(1) Field of the Invention
This invention relates to an anionic matte electrodeposition coating composition and a process for forming a matte film preferably on an aluminum material.
(2) Description of the Prior Art
As an example of the electrodeposition coating compositions used for coating the aluminium material, there has been known an acrylic-melamine based water-soluble or water-dispersible coating composition, for example, there is used a water-soluble or water-dispersible coating composition which is obtained by mixing melamine resin as a crosslinking agent with a water-soluble or water-dispersible resin formed by neutralizing a polycarboxylic resin obtained by copolymerization of acrylic acid or methacrylic acid with other acrylic unsaturated monomer and/or ethylenically unsaturated monomer with ammonia or organic amine. The acrylic-melamine based electrodeposition coating composition has widely been used in coating building materials such as an aluminium sash used in the general houses and high buildings due to its good corrosion resistance and weather resistance.
However, although the acrylic-melamine based electrodeposition coating composition exhibits a satisfactory weather resistance when used in the general houses, the electrodeposition coating composition is quite incapable of satisfying recent requirements for durability over a long period of time of several decades when applied to building materials for use in buildings.
On the other hand, there has recently been developed a fluorocarbon polymer-melamine based electrodeposition coating composition as a coating composition capable of forming a highly durable film without being practically used so far because the fluorocarbon polymer is costly.
Further, in the field of the above coating composition, recent diversification in user's need shows a tendency to lose interest in feeling of metallic luster and highly demands matte film which provides grave feeling.